B9. 4 Circulatory System Flashcards
how does the circulatory system work in unicellular organisms
In unicellular organisms, exchange of materials occurs easily by simple diffusion through the cell surface membrane.
how do multicellular organs not respire
In multicellular organisms, diffusion is inadequate for transport.
why does diffusion not work in multicellular organs for respiration
o larger body, reduced surface area to volume ratio
o numerous cells situated deep in the body, far from external environment
what is blood made up of
Blood is made up of plasma, red blood cells, white blood cells and platelets.
what do red blood cells do
• Red blood cells carry oxygen (to be transported to all cells of the body).
what do white blood cells do
• White blood cells are involved in antibody production and phagocytosis.
what do platelets do
• Platelets are involved in blood clotting.
what does plasma do
Plasma is involved both in the transport of blood components and other dissolved substances including hormones, antibodies, urea and carbon dioxide, and in the distribution of heat.
what other substances other than blood does plasma transport
hormones, antibodies, urea and carbon dioxide, and in the distribution of heat.
how does oxygen go from breathing into blood
As blood passes through the lungs, oxygen diffuses from alveoli (air sacs) into the blood.
what happens when haemoglobin reacts with oxygen
combines reversibly with oxygen to form oxyhaemoglobin
what does haemoglobin do
- Haemoglobin combines reversibly with oxygen to form oxyhaemoglobin.
- Red blood cells transport oxyhaemoglobin to all tissues of the body. As blood passes through tissues, oxyhaemoglobin releases oxygen, which diffuses in solution into tissue cells.
what is oxyhaemoglobin able to do
• Red blood cells transport oxyhaemoglobin to all tissues of the body. As blood passes through tissues, oxyhaemoglobin releases oxygen, which diffuses in solution into tissue cells.
what transports oxyhaemoglobin
• Red blood cells transport oxyhaemoglobin to all tissues of the body. As blood passes through tissues, oxyhaemoglobin releases oxygen, which diffuses in solution into tissue cells.
describe the double circulatory system
Blood passes through the heart twice in one complete circuit as it moves from the pulmonary circulation and into the systemic circulation.
what is pulmonary circulation
Pulmonary circulation: linking the lungs to the heart
what is systemic circulation
Systemic circulation: around the body
what are the advantages of a double circulatory system
Blood enters the lungs at a lower pressure than blood leaving the heart > ensures that blood flows slowly through the lungs, allowing sufficient time for it to be fully oxygenated.
Heart pumps oxygenated blood at high pressure to the rest of the body, ensuring oxygenated blood is distributed to tissues quickly > helps maintain high metabolism
how does heart pumping blood at high pressure affect the body
ensuring oxygenated blood is distributed to tissues quickly > helps maintain high metabolism
describe the passage of blood through the heart
superior + inferior vena cava right atrium tricuspid valve right ventricle semilunar valve pulmonary artery (pulmonary arch) lungs pulmonary veins left atrium bicuspid valve left ventricle semilunar valve aorta
what does the superior vena cava collect blood from
blood from head, neck and arms returned by superior (anterior) vena cava
what does the inferior vena cava collect blood from
blood from other parts of body (except lungs) returned by inferior (posterior) vena cava
once oxygenated blood reaches the aorta, how is blood distributed
From aorta, blood is distributed to all parts of the body (except the lungs).
name the 7 steps that describe the passage of blood through the circulatory system
- Deoxygenated blood from various parts of the body is returned to the right atrium.
- Right atrium contracts, blood flows into right ventricle.
- Right ventricle contracts, blood leaves the heart through pulmonary arch and enters the lungs via pulmonary arteries.
- Oxygenated blood from the lungs is brought back to left atrium by pulmonary veins.
- Left atrium contracts, blood flows into left ventricle.
- Left ventricle contracts, blood leaves through aorta.
- From aorta, blood is distributed to all parts of the body(except the lungs).
